Extrude is not behaving as expected
There are a few ways to shrink/fatten a region of an extrusion.. I don't know if this one is exactly in line with your tutorial....


E Extrude the end of the rod to the desired length of the region to be scaled
Now you have a set of faces whose normals you can extrude along ...  Alt select that face ring
Alt E > (Region, Vertex Normals) extrude the
face selection along its faces' normals.




Now, if you have the Transform Orientation set to 'Normal', you can select the faces at either end of the fattened section, and GZZ to adjust its ends.